Presence of mind

You know what is presence of mind?

A prisoner was once told,

“If you tell a lie, we'll hang you and if you tell the truth, we'll shoot you"

The prisoner saved himself by saying,

“You will hang me"

Now if he has told the truth, then they'll have to shoot him and as he had told the truth they can't do that.

And if he has lied then they'll hang him but then it'll become truth.

Thus by using his presence of mind, he was able to save himself.